<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
    <script src = 'jquery-1.12.4.min.js'></script>
    <title>show</title>
    <style>
        *{
            margin: 0;
            padding: 0;
        }
        .bord{
            border: 1px dashed #ee2602;
            width: 90%;
            margin: 20px auto;
        }
        .title{
            font-size: 20px;
            font-weight: bold;
            margin: 20px;
        }
        .introduce{
            font-size: 16px;
            margin: 0 0 20px 50px;
        }
        .red{
            color: red;
        }
    </style>
    <script>
        jQuery(function ($) {
            $('#mybtn').click(function () {
                $("#a").show()
            })
        });
    </script>
</head>
<body>
<div class="bord">
    <div class="title">show</div>
    <div class="introduce">显示隐藏的匹配元素。</div>
</div>
<div class="bord">
    <div class="title">演示效果</div>
    <div class="introduce">
        <p id="a" style="display: none">Hello</p>
        <button id="mybtn">显示隐藏P标签</button>
    </div>
</div>
<div class="bord">
    <div class="title">代码</div>
    <div class="introduce">
        <pre>
&lt;script&gt;
    jQuery(function ($) {
        $('#mybtn').click(function () {
            $("#a").<a class="red">show()</a>
        })
    });
&lt;/script&gt;
            <br/>
&lt;div class="introduce"&gt;
    &lt;p id="a" style="display: none"&gt;Hello&lt;/p&gt;
    &lt;button id="mybtn"&gt;显示隐藏P标签&lt;/button&gt;
&lt;/div&gt;
        </pre>
    </div>
</div>
</body>
</html>